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Polyunsaturated fatty acids (PUFAs) play an important role in promoting brain development, decreasing the incidence of cardiovascular diseases, and reducing inflammation. However, PUFAs are inherently unstable and susceptible to oxidative deterioration due to two or more double bonds in their structure. Delivery systems have been developed to provide effective encapsulation and protection for PUFAs, and finally fulfill their health benefits. Emulsion-based encapsulation is one of the most promising techniques for the delivery of PUFAs. The emulsion composition and structure, as well as the storage conditions are regarded as key factors to influence the stability of emulsions. To maximize the resistance of PUFAs in emulsions against oxidation, emulsion structure design has been particularly highlighted, and different methods for tailoring emulsion structure have been developed. The current work is focused on the careful design of emulsion structure to improve the oxidative stability of PUFAs. Different types of emulsions, including conventional emulsions, multilayer emulsions, gelled emulsions, and Pickering emulsions are introduced, and their protective effect for PUFAs are discussed. The major role of interfacial structure in emulsions is emphasized. The effects of emulsifiers and involved modification methods on the interfacial structure are presented to further improve the stability of PUFAs during storage., (© 2020 Institute of Food Technologists®.)

In this study, peanut, sesame, and rapeseed oil bodies (OBs) were extracted by the aqueous medium method. The surface protein composition, microstructure, average particle size d 4 , &nbsp; 3 , ζ -potential of the extracted OBs in aqueous emulsion were characterized. The stability of the OB emulsions was investigated. It was found that different OB emulsions contained different types and contents of endogenous and exogenous proteins. Aggregation at low pHs (<6) and creaming at high pHs (7 and 8) both occurred for all of three OB emulsions. Sodium alginate (ALG) was used to solve the instability of OB emulsions under different conditions-low concentration of ALG improved the stability of OB emulsions below and near the isoelectric point of the OBs, through electrostatic interaction. While a high concentration of ALG improved the OB emulsion stability through the viscosity effect at pH 7. The OB emulsions stabilized by ALG were salt-tolerant and freeze-thaw resistant.

In this study, the influence of Persian gum (PG) on the properties of whey protein concentrate (WPC) emulsion gel prepared through cold set gelation method (incorporation of CaCl 2 ) was investigated. The mean droplet size of emulsions was analyzed prior to gelation and the emulsion gel samples were characterized by rheological studies, scanning electron microscopy (SEM) and water holding capacity (WHC) measurement. Results showed PG affected the droplet size of the initial emulsions and the matrix of gel systems. Emulsions containing 0.3% w/w PG revealed higher heat stability compared to the control. A viscoelastic behavior was observed for all emulsion gels with G' being greater than G″ over the whole frequency range tested. Increasing the concentration of PG led to a change in the gel structure at pH 7. SEM images exhibited that PG at 0.3% w/w gave rise to an ordered honeycomb-like microstructure with an interconnected porous matrix of thin walls. In contrast, adding 0.6% w/w PG resulted in a non-uniform network with large pores of thick and rough walls and reduced the WHC. These findings suggest the viscoelastic properties and microstructure of WPC emulsion gel can be tailored by adjusting PG concentration for food formulations., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Gum Acacia Seyal (ASY) is less valued than is gum Acacia Senegal, due to its poor emulsifying ability. The present study investigated the Maillard reaction between ASY and β-lactoglobulin (BLG) and its impact on the emulsifying properties of ASY. The reaction products of BLG/ASY mixture (r=1/4), prepared by dry-heating at 60°C and a relative humidity of 79%, as a function of incubation time, were characterized by SDS-PAGE, GPC-MALLS and DSC. The results showed that 12-24h of dry-heating under the given conditions was sufficient for conjugation, meanwhile avoiding the formation of deeply coloured and insoluble melanoidins. More than 64% of the protein was incorporated into ASY, resulting in a two-fold increase in arabinogalactan-protein (AGP) content and 3.5 times increase in weight-average molecular mass of ASY. The conjugation with BLG markedly improved the stability of ASY-stabilized emulsions and their resistance against severe conditions, such as low pH and high saline conditions., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Oil-in-water (O/W) emulsions with varying concentration of oil phase, medium-chain triglyceride (MCT), were prepared using phase-separating gum arabic (GA)/sugar beet pectin (SBP) mixture as an emulsifier. Stability of the emulsions including emulsion phase separation, droplet size change, and oil migration were investigated by means of visual observation, droplet size analysis, oil partition analysis, backscattering of light, and interfacial tension measurement. It was found that in the emulsions prepared with 4.0% GA/1.0% SBP, when the concentration of MCT was greater than 2.0%, emulsion phase separation was not observed and the emulsions were stable with droplet size unchanged during storage. This result proves the emulsification ability of phase-separating biopolymer mixtures and their potential usage as emulsifiers to prepare O/W emulsion. However, when the concentration of MCT was equal or less than 2.0%, emulsion phase separation occurred after preparation resulting in an upper SBP-rich phase and a lower GA-rich phase. The droplet size increased in the upper phase whereas decreased slightly in the lower phase with time, compared to the freshly prepared emulsions. During storage, the oil droplets exhibited a complex migration process: first moving to the SBP-rich phase, then to the GA-rich phase and finally gathering at the interface between the two phases. The mechanisms of the emulsion stability and oil migration in the phase-separated emulsions were discussed., (© 2016 Institute of Food Technologists®)

Consumers are becoming increasingly fastidious in demanding food products with improved quality and functionality. This largely relies on rational design of food structures. As the two key food ingredients, protein and polysaccharides play important roles in food structuring. The combination of protein and polysaccharide provides rich opportunities for food structure and function designs through molecular interaction and assembly. This paper provides a brief review on the formation and characterization of protein/polysaccharide electrostatic complexes and their applications in stabilizing oil-in-water emulsions, particularly those containing polyunsaturated fatty acids.

The emulsification performance, stability and competitive adsorption of two natural food emulsifiers, sugar beet pectin (SBP) and hydroxypropyl methylcellulose (HPMC) have been investigated. Both can reduce the surface tension and emulsify oil in water. However, due to their different structure and conformation they operate via different mechanisms. Using 15% middle chain triglycerides (MCTs) oil, the amounts of SBP and HPMC adsorbed in emulsions made with these individually and in mixtures were determined. The interfacial concentration (Γ) for SBP stabilized emulsion was ∼1.25mg/m(2) and for HPMC 3.5mg/m(2). The higher adsorption of HPMC was due to multilayer adsorption, whereas SBP adsorbed as a monolayer. Competitive adsorption between SBP and HPMC was also investigated. When the HPMC concentration approached that of adsorbed SBP, the effect of HPMC became dominant and at 1.5wt.% controlled the behavior of the mixed emulsions, which were then almost independent of SBP. The minor role of SBP was mainly to decrease the proportion of large droplets in the emulsion. A model to describe the competitive adsorption between SBP and HPMC is proposed., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

In a previous study (Langmuir 28 (2012) 10164-10176.), we investigated the complexation of bovine serum albumin (BSA) with sugar beet pectin (SBP). A pH-composition phase diagram was established and structural transitions in relation to the phase diagram during complexation were identified. The present study examines the implications of these interactions on the emulsifying performance of BSA/SBP mixtures. Middle-chain triglycerides (MCTs) in water emulsions were prepared using conditions corresponding to different regions of the phase diagram. At high pHs and in the stable region of mixed individual soluble polymers where complexation is absent, there is no improved emulsifying performance, compared with the individual protein and polysaccharide. For these mixtures, the emulsion characteristics are controlled by the major component in the solutions, as determined by the competitive adsorption of the two components at the oil-water interface. At low pHs and low BSA/SBP ratios, and so mainly within the stable region of intramolecular soluble complexes, BSA/SBP mixtures greatly improve the stability of emulsions. Here, stabilisation is controlled by the cooperative adsorption of the two components at the oil-water interface. Through electrostatic complexation BSA promotes the adsorption of SBP on to interfaces to form a thick steric layer around emulsion droplets and thus providing better stability. At low pHs and high BSA/SBP ratios, that is, mainly within the unstable region of intermolecular insoluble complexes, emulsions prepared are extremely unstable due to bridging flocculation between emulsion droplets., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Numerous literatures have shown the advantages of Pickering emulsion (PE) for the delivery of bioactive ingredients in the fields of food, medicine, and cosmetics, among others. On this basis, the multi‐loading mode of bioactives (internal phase encapsulation and/or loading at the interface) in small molecular bioactives nanocrystal‐stabilized PE (BNC‐PE) enables them higher loading efficiencies, controlled release, and synergistic or superimposed effects. Therefore, BNC‐PE offers an efficacious delivery system. In this review, we briefly summarize BNC‐PE fabrication and characterization, with a focus on the processes of possible evolution and absorption of differentially applied BNC‐PE when interacting with the body. In addition, methods of monitoring changes and absorption of BNC‐PE in vivo, from the nanomaterial perspective, are also introduced. The purpose of this review is to provide an accessible and comprehensive methodology for the characterization and evaluation of BNC‐PE after formulation and preparation, especially in relation to biological assessment and detailed mechanisms throughout the absorption process of BNC‐PE in vivo. [ABSTRACT FROM AUTHOR]

Some research activities at Phillips Hydrocolloids Research Centre in Wrexham, Wales and in Wuhan, China have been overviewed. Historical development in both laboratories is described. Most extensively studied topics, the relation between structure and physico-chemical properties of gum Arabic, alginates, konjac glucomannan, carrageenans, beta-lactoglobulins, protein-polysaccharide interactions have been highlighted. [ABSTRACT FROM AUTHOR]

Emulsion-templating techniques have been used to develop structurally anisotropic hydrogels. This paper proposes a method to couple biopolymer assembly behavior with a phase-separated aqueous two-phase system (ATPS) to construct a hierarchical structure on protein-polysaccharide hydrogels. Based on the phase separation of Artemisia sphaerocephala Krasch polysaccharide (ASKP) and whey protein isolate (WPI) fibrils, a bi-continuous hydrogel was fabricated through spontaneous iron-facilitated molecular chelation. The impact of WPI fibrils under ultrasonic treatment for varying durations on gel structurization and physicochemical properties was also exploited. Shorter length of WPI fibrils facilitated stepwise cross-linking gelation during the oxidation of ferrous ions to ferric ions. Specifically, ultrasonic treatment for 6 min and 8 min promoted the accumulation of shorter fibrils, resulting in the formation of a more intensive clockwise-oriented hierarchical network. Compared to the hydrogels with longer linear aggregates without the ultrasonic treatment, the incorporation of the shorter aggregates resulting from ultrasonic treatment for 6 min and 8 min significantly increased the gel's water holding capacity and mechanical properties. Additionally, the fibrils that underwent ultrasonic treatment for 6 min resulted in a more stable three-dimensional network with optimal elastic performance. This study presents a new water-in-water emulsion-templated strategy for structural regulation and stabilization of multiform hydrogel. [Display omitted] • A hierarchical structured hydrogel was created using a phase-separated ATPS. • WPI fibril length effectively impacted the properties of the hierarchical hydrogel. • Shorter fibrils resulted in an oriented network, improving the mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: The bioavailability of lipids from an emulsion can be controlled and regulated by the property of the stabilizing interfacial layer. Here we evaluate how low-molecular weight surfactants including hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 (T80) influence the interfacial behavior of lipase and bile extract on the surface of lipid droplets stabilized with gum arabic (GA). The lipolysis behavior was influenced by surfactant type and concentration. The results showed that anionic SDS could completely displace GA from droplet surface. Cationic CTAB might either adsorb onto existing GA layers or displace GA, whereas non-ionic T80 could co-adsorb with GA on the interface. When the concentration of surfactants was much higher than the critical micelle concentration (CMC), all the surfactants would form a dense adsorption layer on the droplet interface to prevent lipase from the direct contact with lipids. A considerable amount of surfactant in the aqueous phase may also compete with the bile salt and lipase, thus leading to suppressed digestion of lipids. Ionic surfactants would denature the lipase resulting in reduced enzyme activity, and T80 micelles may interact with the lipase, hindering their adsorption onto the droplet interface as well. These results were confirmed both by the digestion model and interfacial techniques. The results provided guidance for the development of emulsion-based delivery systems for functional lipid foods. [Copyright &y& Elsevier]

A novel strategy to enhance the color intensity of β -carotene (BC), namely, "interfacial enriching", was developed in this work. As the sole emulsifier in W/O emulsion, BC particles were enriched onto the droplet surface through emulsifying process. By increasing the concentration of BC in oil phase from 1 mg/g to 5 mg/g, the average droplet size of the emulsion decreased from 92.2 ± 5.1 μm to 34.0 ± 5.4 μm. Too low (e.g. ≤ 1 mg/g) or too high (e.g. ≥25 mg/g) concentration of BC in the oil phase yielded an insufficient coverage or flocculation of the droplets. By enriching onto the interface, the color intensity of BC were enhanced apparently at the reflectance wavelength ranging from 500 nm to 700 nm, compared with that of the BC encapsulated within the emulsion droplets. This enhancement was due to the higher availability of incident light for the BC particles on the interface than that of the BC particles buried inside the droplets. [ABSTRACT FROM AUTHOR]

Lipid digestion is the process of enzymatic hydrolysis at the interface, and the interfacial structure play an important role in the lipid digestion. Non-ionic surfactant Tween80 (T80) presented a significant impact on the lipid digestion of gum Arabic (GA) stabilized oil-in-water emulsion. The interfacial structure of GA-T80 emulsion droplets has been investigated by using gel permeation chromatography-multiangle laser light scattering, interfacial measurement and atomic force microscope. With addition of T80, the surface loading of GA decreased until a plateau value reached. About 15% of GA still remained on the interface when T80 concentration increased to ∼4%. Addition of T80 contributed to a stiffening of the network formed at the droplets interface. The kinetics of lipid digestion exhibited a biphasic rate under this certain interface, shown as an induction period followed by a speeding up process. It probably resulted from the adsorption behavior of lipase on the emulsion interface during the lipolysis process. In was found that the accumulation of lipase on the emulsion droplets interface contributed to the lag period of the free fatty acids release. The biphasic rate of lipid digestion was mainly caused by the rate of lipase adsorption, which was highly dependent on the interface structure of emulsion droplets. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple method to observe the oxygen diffusion in the emulsion system was developed. • The oxygen diffusion was strongly related to the lipid oxidation in emulsion. • The emulsion droplet surface could affect the oxygen diffusion and lipid oxidation. • The oil phase and water phase could affect the oxygen diffusion and lipid oxidation. Oxygen diffusion played an important role in the lipid oxidation of food emulsions. In this study, a simple method was developed to quantitatively observe the oxygen diffusion in the oil–water biphasic system, and it was further applied to investigate the relationship between the oxygen diffusion and lipid oxidation in O/W emulsions. Various factors that related to the emulsion oxidation were considered, from their influence on the oxygen diffusion and lipid oxidation in the emulsions. Results showed that there was obvious correlation between the oxygen diffusion and lipid oxidation in O/W emulsions, which reveals the inhibition of oxygen diffusion could apparently slow down the lipid oxidation. Moreover, the changes of oil phase, water phase and interfacial layer of the emulsions, which were related to the oxygen diffusion, could improve the oxidative stability of the emulsions effectively. Our findings are helpful for deep understanding the mechanisms of the lipid oxidation in food emulsions. [ABSTRACT FROM AUTHOR]

Interaction between β -lactoglobulin fibrils (BLGF) and dipalmitoyl phosphatidylcholine (DPPC) and its effect on the interfacial and emulsifying properties of BLGF were investigated at pH 7. Incorporation of a small amount of DPPC (DPPC/BLGF ratio < 1:10,000) led to the formation of brush-like complexes in which the fibrils were partially coated with a layer of DPPC. This interaction mode was favorable for the adsorption of fibrils onto the oil-water interface, resulting in a thicker and protruding interfacial layer with higher viscoelasticity. On the contrary, incorporation of excessive amount of DPPC (DPPC/BLGF ratio > 1:10) led to the formation of pearl-necklace-like complexes in which the fibrils were heavily and irregularly coated with DPPC surface micelles. This interaction mode tended to reduce the adsorption of fibrils onto the oil-water interface and thus impair the resulting interfacial viscoelasticity. Emulsifying performance of DPPC/BLGF complexes was found to be related to the different interaction modes and interfacial properties. The incorporation of a small amount of DPPC helped to reduce the particle size of BLGF-stabilized emulsions, whereas a high loading of DPPC gave coarse and unstable emulsions that destabilized within one-week storage at ambient temperature. [ABSTRACT FROM AUTHOR]

Anisotropic particles exhibited unique interfacial properties, but only limited types of these particles are available for the food industry. Protein fibrils as anisotropic particles were surface active and expected to function in food systems. For this purpose, we utilize dialyzed and lyophilized β -lactoglobulin ( β -Lg) fibrils to fabricate stable oil-in-water Pickering emulsions at different fibrils concentrations and pHs. Our results demonstrated that β -Lg fibrils were able to stabilize oil-in-water emulsion as observed by fluorescence microscopy. The average droplet size ( d 3,2 ) of the formed emulsions was between 11.0 and 19.0 μm, when homogenized with Ultra Turrax homogenizer at 20,000 rpm for 2 min. The formed emulsions showed an excellent physical stability, which did not coalesce during 56 days storage under ambient temperature, at appropriate fibrils concentrations (5 mg/mL-20 mg/mL) and pHs far from the pI of β -Lg fibrils. At pHs near to its pI (pH 5.2) or with excessive fibrils concentration (≥25 mg/mL), fibrils tended to aggregate, resulting in coarse emulsions with large droplet size. [ABSTRACT FROM AUTHOR]

The physiochemical properties of peanut oil bodies were studied, which was reflected in zeta potential, particle size, and stability. Zeta potential of oil bodies changed from around +37.23 mV at pH 3 to −21.83 mV at pH 7. High temperature (95 °C) did not influence zeta potential and particle size whereas low temperature (−20 °C) lead to the increase in particle sizes of peanut oil body suspension at both pH 3 and 7. However, the effects of low temperature on the particle size were weakened by the addition of gum arabic (GA). Thus, the peanut oil bodies were proved to be a new useful source of lipids for application in emulsion system. The peanut oil bodies can be a food ingredient applied in food industry and gum arabic (GA) could enhance the stability of peanut oil body under several environments. [ABSTRACT FROM AUTHOR]

Conjugated linoleic acid (CLA) is a dietary supplement due to its multiple health benefits. However, significant loss of biologically active CLA could occur due to oxidation. Oil-in-water emulsion is supposed to be an effective protection system. In a previous study (Yao et al., 2013), physical and chemical stabilities of CLA emulsion stabilized with gum Arabic were investigated, and the optimal gum concentration was identified as 5 wt%. The present study dealt with the interfacial adsorption of three gum Arabic samples (one conventional gum, GA; two matured gums, EM2 and EM10) at the CLA-water interface, in relation to their emulsifying properties. With increasing gum Arabic concentration, particle size ( D [3,2]) of CLA emulsion decreased and slowly leveled off, which was accompanied with a gradual saturation of gum Arabic adsorbed at the emulsion interface. Nevertheless, surface load of gum Arabic at the emulsion interface ( Γ , mg/m 2 ) reached maximum at a gum concentration of 5 wt%. This could reasonably explain the optimal emulsion stability observed at this gum concentration, as revealed by particle size distribution of fresh emulsions and by acceleration test at 60 °C. Among the three gums, EM10 exhibited the highest emulsifying activity and conferred the best emulsion stability, despite of its lowest surface load. This is presumably due to a larger tendency of the AGP fraction in EM10 toward aggregation at the CLA-water interface. [ABSTRACT FROM AUTHOR]

Food protein fibrillization is recently regarded as an attractive strategy to broaden and improve food protein functionality in food science. In the present work, whey protein isolate (WPI) solutions was heated at pH 2.0 and 80 °C for different time (1, 2, 4, 8, and 16 h) to prepare whey protein isolate fibrils (WPF), and the resulting WPF was mixed with gum arabic (GA) at pH 2.0–6.0 to explore the properties and functions of such mixtures. The fibril conversion rate of WPI continued to grow from 4% to 32% with the extension of heating time from 1 to 16 h. The phase behavior study showed that the insoluble WPF-GA binary complexes were formed at pH 4.6–6.0 due to the electrostatic interaction between amino groups of WPI and the carboxyl groups of GA. Compared to the WPI-GA complexes, the WPF-GA complexes had a higher GA content and coacervate yield, suggesting that the fibrillization contributes to the association of proteins with polysaccharides. WPF alone were linear, while fibril bundles appeared in the presence of GA. Such WPF-GA complexes exhibited an excellent capacity to prepare gel-like emulsions. The viscosity and strength of the prepared emulsions was gradually enhanced as the fibril conversion rate of WPI increased. Besides, the complexes of GA and WPF with a heat-treated time of 16 h showed the greatest potential to prepare mayonnaise analogues with a solid-like property, which possessed the similar storage modulus and smoothness to the commercial mayonnaise products. • Whey protein isolate (WPI) was converted into fibrils (WPF) after heating at pH 2. • The WPI fibrillization contributes to the association of WPF with gum Arabic (GA). • The insoluble WPF-GA complexes was formed due to the electronic interaction. • WPF-GA complexes exhibited an excellent capacity to prepare gel-like emulsions. • WPF-GA complexes showed great potential to prepare mayonnaise analogues. [ABSTRACT FROM AUTHOR]

The production of dried probiotic bacterial cells that are shelf stable at room temperature remains challenging. In this work, the potential of encapsulation of probiotic Lactobacillus reuteri using heteroprotein complex coacervation (type-A gelatin/sodium caseinate, GE/Cas) was compared to a protein/polysaccharide complex coacervation (type-A gelatin/gum arabic, GE/GA). The optimal pH and GE/Cas ratio for formation of water-in-water emulsions were found to be pH = 6.0 and GE/Cas = 2.0. L. reuteri TMW1.656 survived spray drying without loss of viability; the survival after simulated digestion, heating and ambient storage decreased in the order GE/Cas ≥ Cas > GE/GA > GE. The improved protection of the GE/Cas matrix was related to a reduced hygroscopicity, solubilization and wettability, and may be caused by the relatively higher hydrophobicity of GE/Cas heteroprotein coacervation system. To the best of our knowledge, this is the first study employing heteroprotein coacervation to encapsulate probiotics. Image 1 • Heteroprotein coacervation with W/W emulsion structure was firstly reported. • GE/Cas coacervation provided better probiotic protection than GE/GA coacervation. • Microcapsule properties were related with cell survivals under different stresses. [ABSTRACT FROM AUTHOR]

• Phase separation induces molecular fractionation of GA/hydrocolloids mixtures. • Molecular fractionation increased the AGP content GA. • Emulsifying functionality of GA improved after phase separation. The emulsification properties of the standard (STD), matured (EM2 and EM10) and fractionated gum arabic samples via phase separation induced molecular fractionation were investigated to find out how the content of arabinogalactan protein (AGP) complex affects the resulting emulsion properties. Phase separation and the accompanying molecular fractionation were induced by mixing with different hydrocolloids including hyaluronan (HA), carboxymethyl cellulose (CMC), and maltodextrin (MD). Increase of AGP content from 11 to 28% resulted in the formation of emulsions with relatively smaller droplet sizes and better stability. Further increase in the AGP content to 41% resulted in the formation of emulsions with larger droplets. In spite of the larger droplets sizes, these emulsions were extremely stable. In addition, the emulsions prepared with GA higher AGP content better stability in the presence of ethanol. The results indicate that AGP content plays a vital role in emulsion stability and droplet size. [ABSTRACT FROM AUTHOR]